Re: [PATCH v2] usb: mtu3: disable bottom halves in the threaded interrupt handler

[sashiko-bot@kernel.org]

> mtu3_irq() is a threaded handler, so it runs in process context, and it
> takes mtu->lock with spin_lock_irqsave(). mtu3_req_complete() drops the
> lock with a plain spin_unlock() around usb_gadget_giveback_request(), so
> the gadget function's completion callback runs with interrupts disabled,
> as the gadget API promises, but in neither hardirq nor softirq context.
> 
> That breaks any callback that reaches netif_rx(). netif_rx() disables
> bottom halves itself when it is called outside hardirq and softirq
> context, and enabling them again with interrupts disabled is not
> allowed:
> 
>   WARNING: kernel/softirq.c:453 at __local_bh_enable_ip+0x128/0x134
>     __local_bh_enable_ip
>     netif_rx
>     rx_complete [u_ether]
> [ ... ]
> names. The same copy is reliable with this change applied.
> 
> Fixes: 13118959cb1a ("usb: mtu3: register mtu3_irq by threaded irq")
> Cc: stable@vger.kernel.org
> Signed-off-by: Ryan Brue <ryanbrue.dev@gmail.com>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261104-usb-mtu3-gadget-completion-callback-fix-v2-1-2769533a39cb@gmail.com?part=1